Central nervous system bioaminergic responses to mechanical trauma. An experimental study

Pomegranate juice rescues developmental, neurobehavioral and biochemical disorders in aluminum chloride-treated male mice

PURPOSE

Aluminum (Al) is a harmful metal to organisms and is capable of entering the human body in multiple ways, such as through drinking, breathing, deodorant use, and vaccination. This study examined the prospective toxicity of Al and the protective attributes of pomegranate juice (PJ) on neurobehavioral and biochemical parameters of male mice.

METHODS

Six groups of male mice were treated for 35 days with 20 % PJ (group II), 40 % PJ (group III), 400 mg/kg Al (group IV), Al + 20 % PJ (group V), Al + 40 % PJ (group VI) or tap water (control, group I). Behavioral assessments were conducted for learning and memory evaluations at the end of experiment. In addition, the forebrain was isolated for biochemical analysis.

RESULTS

The exposure of male mice to Al decreased learning and memory retention in the shuttle box, Morris water-maze and T-Maze tests. Biochemical analysis revealed significant depletions in neurotransmitters including DA, 5-HT and AChE and oxidative proteins including GSH, GST, CAT and SOD and increased TBARES levels in Al-treated mice compared to untreated mice. Pomegranate juice provided protection against these effects after Al exposure by ameliorating learning and memory retention and oxidative state in a dose-independent manner.

CONCLUSION

Our data demonstrated that Al exposure caused behavioral and biochemical disorders. Pomegranate juice in lower dose has beneficial properties for health and can be used as a source of antioxidants to reduce the toxicity of Al and other substances.

Ameliorating Effects of Lithium on the Perinatal Ethanol-Induced Behavioral and Cognitive Dysfunction and Brain Oxidative Stress in Postnatal Developing Mice Pups

BACKGROUND

Developmental ethanol (EtOH) exposure can cause lifelong behavioral hyperactivity, cognitive deficits, emotional dysregulation, and more. However, co-treatment with lithium (Li) on the day of EtOH exposure prevents many of the impairments.

METHODS

Experimental groups of pregnant mice were exposed to EtOH (20% v/v solution at a dose of 2.5 g/kg) in their drinking water and the animals were treated with Li (15 and 30 mg/kg) through IP injection on gestational days14, 16, 18, and 20, and post-natal days (PD) 3, 5, 7, and 9. All treatments with EtOH and exposure to Li doses to pregnant mice started on gestational day 14 and continued until post-natal day 9 (PD9). The effects on some developing morphological indices, nerve reflexes during weaning age, and various cognitive dysfunctions at adolescent ages and biochemical changes in the brain tissue indices of below-mentioned neurotransmitters and oxidative stress in post-natal developing offspring at adolescent age, were studied.

RESULTS

Perinatal exposure to EtOH in pregnant mice resulted in several postnatal developing and morphological indices in the developing male pups during their weaning period, like gain in their body weight, delay in appearance of their body hair fuzz and opening of their eyes, and disruptions in their developing motor reflexes.

DISCUSSION

During adolescent age, a significant deficit in their learning capability and cognitive behavior, decline in the neurochemical DA and 5-HT in their brain and some indices of oxidative stress TBARS, GSH, GST, CAT, and SOD was observed.

CONCLUSION

These results indicate that Li ameliorates significantly and dose-dependently EtOH induced developmental toxicities like morphological developments and dysfunctions in cognitive retention and oxidative stress on a long-term basis in brain tissue. However, further detailed studies are required for the clinical use of as an ameliorating agent for perinatal EtOH induced dysfunctions.

Neurobehavioral protective properties of curcumin against the mercury chloride treated mice offspring

In the present investigation, the effects of mercuric chloride (HgCl2) on the neurobehavioural and neurochemical disruption in mice offspring was studied. A total of thirty pregnant mice were divided into six groups. Group II and III were received 150 and 300 ppm of curcumin respectively. Group IV was given 10 ppm of HgCl2. Group V and VI were given 10 ppm of HgCl2 with 150 and 300 ppm of curcumin respectively. In this study, treatment started from day one of pregnancy and continued until post-natal day 15 (PD 15). During weaning period, three pups in each experimental group were marked and were subjected to behavioral, physical and biochemical tests. The results revealed decreased body weight, delayed hair growth and eye opening. HgCl2 treated pups taken more time in righting, rotating reflexes to return to normal placement, cliff avoidance compared to that of control group. HgCl2 exposed pups showed memory and learning deficits. Anxiety behavior in treating pups was increased. Biochemical investigations showed decreased level of dopamine (DA), serotonin (5-HT) and acetylcholinesterase (AChE) in forebrain of treated pups compared to the control and curcumin groups. The protective effect of curcumin doses were significant compared to HgCl2 group. The results indicated that the administration of curcumin showed effective activity towards biochemical and behavioral disorders obtained with the HgCl2 treated animals. Overall, the curcumin administration revealed increased cognetion and anxiety behaviors in the treated animals. Conclusively, curcumin has a good benefits for health which can use to avoid toxicants such as Hg and other heavy metals.

The effect of donepezil on the cognitive ability early in the course of recovery from traumatic brain injury

OBJECTIVE

To investigate the effect of donepezil on cognitive ability in patients who have sustained a traumatic brain injury (TBI). We hypothesized that donepezil, an acetylcholinesterase inhibitor, would enhance cognitive recovery beyond that of usual care in an acute rehabilitation facility.

METHODS

This retrospective, longitudinal analysis included 55 patients who were non-randomly prescribed donepezil during acute care and compared them to 74 patients who received usual rehabilitation treatment. All 129 patients completed neuropsychological assessment at two time points. Donepezil was increased from 5 to 10 mg 7-10 days after initiation and maintained until follow-up cognitive assessment.

MAIN OUTCOMES

Primary cognitive abilities of interest included processing speed, attention and memory. Cognitive and functional abilities were assessed by a standard neuropsychological battery for TBI.

RESULTS

Propensity scores were used to adjust for differences between groups. Mixed effect model analysis showed no significant differences between treatment and control groups on all neuropsychological subtests over time.

CONCLUSIONS

Acute administration of donepezil did not significantly improve measures of cognitive or functional ability beyond that of treatment as usual in patients with moderate-to-severe TBI.

Mercuric resistant bacteria Aeromonas exhibits neurologic toxic effects on the developmental motor reflexes, and brain oxidative stress in mice offspring

Mercury and its derivatives even in small concentration may cause a major human health problem. Though not reported in detail, there are various aquatic bacterial species that produce small quantities of methyl mercury (MM) growing under aerobic conditions. Consumption of food derived from sources contaminated with such bacteria within therapeutic doses and exposure to different forms of MM compounds through such sources may induce substantial toxic effects. In the present study, the perinatal oral exposure of pregnant mice to two strains of mercury resistant bacteria (MRB), Aeromonas KSU5 MRB and KSU6 MRB resulted in a significant reduction in postnatal body weight gain, delays in the opening of the eyes and appearance in the body hair fuzz, and deficits in the developing sensory motor reflexes in the mice pups during their weaning period on post-natal day (PD)7, PD14 and PD21. A significant and MM producing concentration-dependent disturbance in the levels of neurotransmitters like dopamine (DA) and serotonin (5-HT); non-enzymatic oxidative stress (OS) indices like thiobarbituric acid-reactive substances (TBARS) and total reduced glutathione (GSH); and enzymatic OS indices like glutathione S-transferase (GST), catalase (CAT), and superoxide dismutase (SOD) were observed in the forebrain region of the offspring at weaning period (PD7, PD14, and PD21), at adolescent age (PD30), and at adult age (PD36). Thus, perinatal exposure to MRB can affect developing fetus, raising the concerns for it's potential neurotoxic hazards. A reduced exposure to mercury during pregnancy is of crucial importance in preventing mercury-induced neurotoxicity in the offspring.

Cardamom (Elettaria cardamomum) perinatal exposure effects on the development, behavior and biochemical parameters in mice offspring

Cardamom is a strong antioxidant plant, so it is called the queen of spices. In the present study, we explored the potentials of cardamom on developmental, learning ability and biochemical parameters of mice offspring. Thirty pregnant mice were allocated to three groups of ten animals in each. Groups Π and Ш received pilsbury's Diet containing 10 and 20% of cardamom (w/w) respectively, whereas Group I used as control. Cardomom was administered from the first day of pregnancy and was continued until post-natal day 15 (PD 15) and thereafter the mothers were switched to plain pilsbury's Diet. During the weaning period, three pups in each litter were color marked from the others, and were subjected to various tests (Physical assessment such body weight and eye opening and hair appearance; the neuromaturation of reflexes like righting, rotating, and cliff avoidance reflexes; learning ability and memory retention; estimation of monoamines neurotransmitters like dopamine and serotonin, non-enzymatic oxidative stress such as TBARS and GSH in forebrain at different ages of pups). The results indicated that the body weight gain was declining significantly. Hair appearance and eyes opening were delayed significantly. Righting, rotating, and cliff avoidance reflexes were delayed in treated animals. Exposure to cardamom led to enhance learning and memory retention as compared to control. Monoamines (DA, 5-HT) and GSH were elevated, whereas TBARS was inhibited significantly. In conclusion, perinatal cardamom exposure enhanced learning and memory as compared to control. Cardamom and its benefit compounds were transported via placenta or/and milk during lactation. Cardamom needs more researches to investigate its benefits on other kinds of behavior.

Simultaneous administration of fluoxetine and simvastatin ameliorates lipid profile, improves brain level of neurotransmitters, and increases bioavailability of simvastatin

Simvastatin (STT), a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, is widely prescribed for dyslipidemia, whereas fluoxetine (FLX) is the first-choice drug for the treatment of depression and anxiety. A recent report suggests that selective serotonin reuptake inhibitors can interact with the cytochrome P450 3A4 substrate, and another one suggests that STT enhances the antidepressant activity of FLX. However, the data are inconclusive. The present study was designed to explore the pharmacokinetic and pharmacodynamic consequences of coadministration of STT and FLX in experimental animals. For this, Wistar rats weighing 250±10 g were divided into four groups, including control, STT (40 mg/kg/day), FLX (20 mg/kg/day), and STT+FLX group, respectively. After the dosing period of 4 weeks, the animals were sacrificed, and the blood and brain samples were collected for the analysis of STT, simvastatin acid (STA), FLX, total cholesterol, triglyceride, high-density lipoprotein (HDL), 5-hydroxytryptamine, dopamine, and hydroxy indole acetic acid. It was found that the coadministration resulted in a significant increase in the bioavailability of STT in the plasma (41.8%) and brain (68.7%) compared to administration of STT alone (p<0.05). The maximum drug concentration (C_max) of STT was also found to be increased significantly in the plasma and brain compared to that achieved after monotherapy (p<0.05). However, STT failed to improve the pharmacokinetics of FLX up to a significant level. The results of this study showed that the combined regimen significantly reduced the level of cholesterol and triglyceride and increased the level of HDL when compared to STT monotherapy. Furthermore, the coadministration of STT with FLX led to an elevated level of neurotransmitters in the brain (p<0.05). FLX increased the concentration of STT in the plasma and brain. The coadministration of these drugs also led to an improved lipid profile. However, in the long-term, this interaction may have a vital clinical importance because the increase in STT level may lead to life-threatening side effects associated with statins.

Pathophysiological links between traumatic brain injury and post-traumatic headaches

This article reviews possible ways that traumatic brain injury (TBI) can induce migraine-type post-traumatic headaches (PTHs) in children, adults, civilians, and military personnel. Several cerebral alterations resulting from TBI can foster the development of PTH, including neuroinflammation that can activate neural systems associated with migraine. TBI can also compromise the intrinsic pain modulation system and this would increase the level of perceived pain associated with PTH. Depression and anxiety disorders, especially post-traumatic stress disorder (PTSD), are associated with TBI and these psychological conditions can directly intensify PTH. Additionally, depression and PTSD alter sleep and this will increase headache severity and foster the genesis of PTH. This article also reviews the anatomic loci of injury associated with TBI and notes the overlap between areas of injury associated with TBI and PTSD.

Oral administration of potassium bromate induces neurobehavioral changes, alters cerebral neurotransmitters level and impairs brain tissue of swiss mice

Background

Potassium bromate (KBrO₃) is widely used as a food additive and is a major water disinfection by-product. The present study reports the side effects of KBrO₃ administration on the brain functions and behaviour of albino mice.

Methods

Animals were divided into three groups: control, low dose KBrO₃ (100 mg/kg/day) and high dose KBrO₃ (200 mg/kg/day) groups.

Results

Administration of KBrO₃ led to a significant change in the body weight in the animals of the high dose group in the first, second and the last weeks while water consumption was not significantly changed. Neurobehavioral changes and a reduced Neurotransmitters levels were observed in both KBrO₃ groups of mice. Also, the brain level of reduced glutathione (GSH) in KBrO₃ receiving animals was decreased. Histological studies favoured these biochemical results showing extensive damage in the histological sections of brain of KBrO₃-treated animals.

Conclusions

These results show that KBrO₃ has serious damaging effects on the central nervous system and therefore, its use should be avoided.

Effectiveness of minocycline and FK506 alone and in combination on enhanced behavioral and biochemical recovery from spinal cord injury in rats

Injury to the spinal cord results in immediate physical damage (primary injury) followed by a prolonged posttraumatic inflammatory disorder (secondary injury). The present study aimed to investigate the neuroprotective effects of minocycline and FK506 (Tacrolimus) individually and in combination on recovery from experimental spinal cord injury (SCI). Young adult male rats were subjected to experimental SCI by weight compression method. Minocycline (50mg/kg) and FK506 (1mg/kg) were administered orally in combination and individually to the SCI group daily for three weeks. During these three weeks, the recovery was measured using behavioral motor parameters (including BBB, Tarlov and other scorings) every other day for 29days after SCI. Thereafter, the animals were sacrificed and the segment of the spinal cord centered at the injury site was removed for the histopathological studies as well as for biochemical analysis of monoamines such as 5-hydroxytryptamine (5-HT) and 5-hydroxy-indolacetic acid (5-HIAA) and some oxidative stress indices, such as thiobarbituric acid-reactive substances (TBARS), total glutathione (GSH) and myeloperoxidase (MPO). All behavioral results indicated that both drugs induced significant recovery from SCI with respect to time. The biochemical and histopathological results supported the behavioral findings, revealing significant recovery in the regeneration of the injured spinal tissues, the monoamine levels, and the oxidative stress indices. Overall, the effects of the tested drugs for SCI recovery were as follows: FK506+minocycline>minocycline>FK506 in all studied parameters. Thus, minocycline and FK506 may prove to be a potential therapy cocktail to treat acute SCI. However, further studies are warranted.

Protective Effect of Parsley Juice (Petroselinum crispum, Apiaceae) against Cadmium Deleterious Changes in the Developed Albino Mice Newborns (Mus musculus) Brain

Parsley was used as a probe of the current experiment to prevent the behavioral, morphological and biochemical changes in the newborn brain following the administration of cadmium (Cd) to the pregnant mice. The nonanesthetized pregnant mice were given daily parsley juice (Petroselinum crispum) at doses of 20 mg/kg and 10 mg/kg. Pregnant mothers were given Cd at a dose of 30 mg/kg divided into 3 equal times. The newborns have been divided into 6 groups: Group A, mothers did not take treatment; Groups B and C, mothers were treated with low and high dose of parsley, respectively; Group D, mothers were treated only with Cd (perinatal intoxication); Groups E and F, mothers were treated with Cd doses and protected by low and high doses of parsley, respectively. Light microscopy showed that Cd-induced neuronal degeneration by chromatolysis and pyknosis in the brain regions. The low dose of parsley 10 g/kg/day exhibited significant effects in neutralizing and reducing the deleterious changes due to Cd exposure during pregnancy on the behavioral activities, neurotransmitters, oxidative stress, and brain neurons morphology of the mice newborns.

Effect of parsley (Petroselinum crispum, Apiaceae) juice against cadmium neurotoxicity in albino mice (Mus musculus)

Background

Parsley was employed as an experimental probe to prevent the behavioral, biochemical and morphological changes in the brain tissue of the albino mice following chronic cadmium (Cd) administration.

Methods

Non-anesthetized adult male mice were given parsley juice (Petroselinum crispum, Apiaceae) daily by gastric intubation at doses of 10 and 20 g/kg/day. The animals were divided into six groups: Group A, mice were exposed to saline; Groups B and C, were given low and high doses of parsley juice, respectively; Group D, mice were exposed to Cd; Groups E and F, were exposed to Cd and concomitantly given low and high doses of parsley, respectively.

Results

Cd intoxication can cause behavioral abnormalities, biochemical and histopathological disturbances in treated mice. Parsley juice has significantly improved the Cd-associated behavioral changes, reduced the elevation of lipid peroxidation and normalized the Cd effect on reduced glutathione and peroxidase activities in the brain of treated mice. Histological data have supported these foundations whereas Cd treatment has induced neuronal degeneration, chromatolysis and pyknosis in the cerebrum, cerebellum and medulla oblongata.

Conclusion

The low dose (5 g/kg/day) of parsley exhibited beneficial effects in reducing the deleterious changes associated with Cd treatment on the behavior, neurotransmitters level, oxidative stress and brain neurons of the Cd-treated mice.

Cognitive and biochemical effects of monosodium glutamate and aspartame, administered individually and in combination in male albino mice

The present study was designed to investigate the in vivo effects of monosodium glutamate (MSG) and aspartame (ASM) individually and in combination on the cognitive behavior and biochemical parameters like neurotransmitters and oxidative stress indices in the brain tissue of mice. Forty male Swiss albino mice were randomly divided into four groups of ten each and were exposed to MSG and ASM through drinking water for one month. Group I was the control and was given normal tap water. Groups II and III received MSG (8 mg/kg) and ASM (32 mg/kg) respectively dissolved in tap water. Group IV received MSG and ASM together in the same doses. After the exposure period, the animals were subjected to cognitive behavioral tests in a shuttle box and a water maze. Thereafter, the animals were sacrificed and the neurotransmitters and oxidative stress indices were estimated in their forebrain tissue. Both MSG and ASM individually as well as in combination had significant disruptive effects on the cognitive responses, memory retention and learning capabilities of the mice in the order (MSG+ASM)>ASM>MSG. Furthermore, while MSG and ASM individually were unable to alter the brain neurotransmitters and the oxidative stress indices, their combination dose (MSG+ASM) decreased significantly the levels of neurotransmitters (dopamine and serotonin) and it also caused oxidative stress by increasing the lipid peroxides measured in the form of thiobarbituric acid-reactive substances (TBARS) and decreasing the level of total glutathione (GSH). Further studies are required to evaluate the synergistic effects of MSG and ASM on the neurotransmitters and oxidative stress indices and their involvement in cognitive dysfunctions.

Protective effect of methanolic extract of Garcinia indica fruits in 6-OHDA rat model of Parkinson's disease

CONTEXT

Several studies have reported that antioxidants play an important role in Parkinson's disease (PD). Garcinia indica extract is a natural antioxidant, the present study was undertaken to evaluate the neuroprotective effect of methanolic extract of Garcinia indica (GIM) against 6-hydroxydopamine (6-OHDA) neurotoxicity for striatal dopaminergic neurons in the rat.

MATERIALS AND METHODS

Thirty adult Wistar rats were randomly divided into five groups namely control, 6-OHDA model, and GIM (100, 200, and 400 mg/kg body weight suspended in one ml of 0.1% carboxymethyl cellulose). The treatment was started three days before surgery and continued for next 14 days. The surgery was done on third day in all groups for administration of 6-OHDA into the right striatum and right substantia nigra, whereas control group injected with 6-OHDA vehicle. Various behavior and biochemical tests (Apomorphine-induced rotational behavior, Stepping test, Initiation time, Postural balance test, and Disengage time) were used to evaluate the neuroprotective effect of GIM. One-way analysis of variance (ANOVA) followed by Dunnett's test was used to compare inter-group differences. P<0.05 was considered as statistically significant.

RESULTS

GIM had significant (P<0.05, P<0.01) preventive effect in biochemical tests, i.e., dopamine and its metabolites measurement and in various behavior tests, i.e., apomorphine-induced rotational behavior, stepping test, initiation time, postural balance test, and disengage time as compared to 6-OHDA-treated rats.

CONCLUSIONS

Our results demonstrated that GIM acted as an effective neuroprotective agent for striatal dopaminergic neurons in 6-OHDA lesioned rat model of PD.

Trolox ameliorates 3-nitropropionic acid-induced neurotoxicity in rats

3-nitropropionic acid (3-NPA) is a naturally occurring neurotoxin produced by legumes of the genus Astragalus and Arthrium fungi. Acute exposure to 3-NPA results in striatal astrocytic death and variety of behavior dysfunction in rats. Oxidative stress has been reported to play an important role in 3-NPA-induced neurotoxicity. Trolox is a potent free radical chain breaking antioxidant which has been shown to restore structure and function of the nervous system following oxidative stress. This rapid and efficient antioxidant property of trolox was attributed to its enhanced water solubility as compared with alpha-tocopherol. This investigation was aimed to study the effect of trolox against 3-NPA-induced neurotoxicity in female Wistar rats. The animals received trolox (0, 40 mg, 80 mg and 160 mg/kg, orally) daily for 7 days. 3-NPA (25mg/kg, i.p.) was administered daily 30 min after trolox for the same duration. One additional group of rats served as control (vehicle only). On day 8, the animals were observed for neurobehavioral performance. Immediately after behavioral studies, the animal's brains were dissected out for histological studies. Lesions in the striatal dopaminergic neurons were assessed by immunohistochemical method using tyrosine hydroxylase immunostaining. Administration of 3-NPA alone caused significant depletion of striatal dopamine and glutathione, whereas, the levels of thiobarbituric acid reactive substance (TBARS) and nitric oxide (NO) were significantly increased suggesting an elevated level of oxidative stress. Trolox significantly and dose-dependently protected animals against 3-NPA-induced neurobehavioral, neurochemical and structural abnormalities. These results clearly suggest that protective effect of trolox against 3-NPA-induced neurotoxicity is mediated through its free radical scavenging activity.

Pentoxifylline ameliorates lithium-pilocarpine induced status epilepticus in young rats

The neuroprotective effects of pentoxifylline (PTX) against lithium-pilocarpine (Li-Pc)-induced status epilepticus (SE) in young rats are described. Animals treated with PTX (0, 20, 40, and 60 mg/kg) before induction of SE were examined for latency to and frequency of SE, behavioral changes, oxidative stress, neurochemical alterations in the hippocampus and striatum, and histological abnormalities in the hippocampus. Treatment with PTX significantly ameliorated the frequency and severity of epileptic seizures in a dose-dependent manner. Our behavioral studies using the elevated plus-maze, rotarod, and water maze tests suggested a significant reduction in anxiety, enhanced motor performance, and improved learning and memory in PTX-treated rats. Li-Pc-induced neuronal cell loss and sprouting of mossy fibers in the hippocampus were also attenuated by PTX. The neuroprotective activity of PTX was accompanied by reduction in oxidative stress and reversal of SE-induced depletion of dopamine and 5-hydroxytryptamine in hippocampus and striatum. The results of this study provide a good rationale to explore the prophylactic/therapeutic potential of PTX in SE.

Effect of repetitive ischemic preconditioning on spinal cord ischemia in a rabbit model

A completely randomized controlled study based on a rabbit model was designed to study the effect of repetitive ischemic preconditioning (IPC) on a spinal cord ischemic reperfusion injury. Twenty four white adult Japanese rabbits were randomly assigned to one of the 3 groups (n = 8 per group): Group I: sham-operation group, Group II: ischemic reperfusion group, and, Group III: IPC group. Spinal cord ischemia was induced by infra-renal aortic cross-clamp for 45 min in Group II. Before 45 min ischemia, the rabbits in Group III underwent four cycles of IPC (5 min of ischemia followed by 5 min of reperfusion). Post-operative neurological function, electromyography (EMG) of rear limbs, and spinal cord histopathological changes were measured. The concentrations of calcium, magnesium, copper, and zinc in spinal cord were measured in the 7th day. The neurological function and histopathological changes in Group II were significantly different from those in Group I or Group III (P < 0.05 or 0.01). There was a more significant change of EMG in Group II than that in Group III (P < 0.05). The concentrations of calcium and copper in Group II were significantly higher (P < 0.05 or 0.01), but magnesium and zinc were significantly lower (P < 0.05) than those in Group I. Calcium and copper in Group II were significantly higher (P < 0.05), but zinc was significantly lower (P < 0.01) than those in Group III. In conclusion, repetitive IPC can protect rabbit spinal cord from ischemic reperfusion injury in a timely manner, which is associated with corrections of imbalance of calcium, magnesium, copper, and zinc in the ischemic region.

Neuroprotective effect of nicotine against 3-nitropropionic acid (3-NP)-induced experimental Huntington's disease in rats

Nicotinic acetylcholine receptors (nAChRs) are regarded as potential therapeutic targets to control various neurodegenerative diseases. Owing to the relevance of cholinergic neurotransmission in the pathogenesis of Huntington's disease (HD) this investigation was aimed to study the effect of nicotine, a nAChR agonist, on 3-nitropropionic acid (3-NP)-induced neurodegeneration in female Wistar rats. Systemic administration of 3-NP in rats serves as an important model of HD. The animals received subcutaneous injections of nicotine (0, 0.25, 0.50 and 1.00 mg/kg) daily for 7 days. 3-NP (25 mg/kg, i.p.) was administered daily 30 min after nicotine for the same duration. One additional group of rats served as control (vehicle only). On day 8, the animals were observed for neurobehavioral performance (motor activity, inclined plane test, grip strength test, paw test and beam balance). Immediately after behavioral studies, the animals were transcardially perfused with neutral buffered formalin (10%) and brains were fixed for histological studies. Lesions in the striatal dopaminergic neurons were assessed by immunohistochemical method using tyrosine hydroxylase (TH) immunostaining. Treatment of rats with nicotine significantly and dose-dependently attenuated 3-NP-induced behavioral deficits. Administration of 3-NP alone caused significant depletion of striatal dopamine (DA) and glutathione (GSH), which was significantly and dose-dependently attenuated by nicotine. Preservation of striatal dopaminergic neurons by nicotine was also confirmed by immunohistochemical studies. These results clearly showed neuroprotective effect of nicotine in experimental model of HD. The clinical relevance of these findings in HD patients remains unclear and warrants further studies.

Applications of the P50 evoked response to the evaluation of cognitive impairments after traumatic brain injury

This article reviews the applications of the P50 evoked response to paired auditory stimuli (P50 ERP) in the study and evaluation of cognitive impairments after traumatic brain injury (TBI). The cholinergic hypothesis of cognitive impairment after TBI and the relationship of impaired auditory sensory gating to that hypothesis are presented. The neurobiology of impaired sensory gating, the relationship of that neurobiology to the P50 ERP, and the principles of P50 ERP recording are discussed. Studies of the P50 ERP among patients with persistent cognitive complaints after TBI are reviewed. Finally, possible clinical applications and limitations of the P50 ERP in the study, evaluation, and treatment of patients with cognitive impairments after TBI are offered.

The cholinergic hypothesis of cognitive impairment caused by traumatic brain injury

Cognitive impairments are among the most common neuropsychiatric sequelae of traumatic brain injury at all levels of severity. Cerebral cholinergic neurons and their ascending projections are particularly vulnerable to acute and chronic traumatically mediated dysfunction. In light of the important role of acetylcholine in arousal, attention, memory, and other aspects of cognition, cerebral cholinergic systems contribute to and may also be a target for pharmacologic remediation among individuals with post-traumatic cognitive impairments. This article will review the evidence in support of this hypothesis. Evidence of relatively selective damage to cholinergic injury, the development of persistent anticholinergic sensitivity, and the effects of cholinergic augmentation on memory performance are presented first. Thereafter, neuropathologic, electrophysiologic, and pharmacologic evidence of cholinergic dysfunction after traumatic brain injury in humans is reviewed. Finally, future directions for investigation of the cholinergic hypothesis and possible clinical applications of this information are discussed.

Cognitive Impairment Following Traumatic Brain Injury

Cognitive impairments due to traumatic brain injury (TBI) are substantial sources of morbidity for affected individuals, their family members, and society. Disturbances of attention, memory, and executive functioning are the most common neurocognitive consequences of TBI at all levels of severity. Disturbances of attention and memory are particularly problematic, as disruption of these relatively basic cognitive functions may cause or exacerbate additional disturbances in executive function, communication, and other relatively more complex cognitive functions. Because of the high rate of other physical, neurologic, and psychiatric syndromes following TBI, a thorough neuropsychiatric assessment of the patient is a prerequisite to the prescription of any treatment for impaired cognition. Psychostimulants and other dopaminergically active agents (eg, methylphenidate, dextroamphetamine, amantadine, levodopa/carbidopa, bromocriptine) may modestly improve arousal and speed of information processing, reduce distractibility, and improve some aspects of executive function. Cautious dosing (start-low and go-slow), frequent standardized assessment of effects and side effects, and monitoring for drug-drug interactions are recommended. Cognitive rehabilitation is useful for the treatment of memory impairments following TBI. Cognitive rehabilitation may also be useful for the treatment of impaired attention, interpersonal communication skills, and executive function following TBI. This form of treatment is most useful for patients with mild to moderate cognitive impairments, and may be particularly useful for those who are still relatively functionally independent and motivated to engage in and rehearse these strategies. Psychotherapy (eg, supportive, individual, cognitive-behavioral, group, and family) is an important component of treatment. For patients with medication- and rehabilitation-refractory cognitive impairments, psychotherapy may be needed to assist both patients and families with adjustment to permanent disability.

Protective effect of quinacrine on striatal dopamine levels in 6-OHDA and MPTP models of Parkinsonism in rodents

Recent studies provide evidence that phospholipase A2 (PLA2) may play a role in the development of experimental parkinsonism. In this investigation an attempt was made to determine a possible protective effect of quinacrine (QNC), a PLA2 inhibitor on MPTP as well as 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in rodents. For MPTP studies, adult male mice (C57 BL) were treated with MPTP (30 mg/kg, i.p.) daily for 5 days. QNC was injected i.p. in the doses of 0, 10, 30 and 60 mg/kg daily 30 min before MPTP in four different groups. Two other groups of mice received either vehicle (control) or a high dose of QNC (60 mg/kg). Two hours after the last injection of MPTP, striata were collected for the analysis of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and glutathione (GSH). For the 6-OHDA study, male Wistar rats were infused with 6-OHDA (60 microg) in the right striatum under chloral hydrate anesthesia. The rats in different groups were treated with 0, 5, 15 and 30 mg/kg QNC (i.p.) for 4 days, while first injection was given 30 min before 6-OHDA. On day 5, rats were sacrificed and striata were stored at -80 degrees C. Administration of MPTP or 6-OHDA significantly reduced striatal DA, which was significantly attenuated by QNC. Concomitant treatment with QNC also protected animals against MPTP or 6-OHDA-induced depletion of striatal GSH. Our findings clearly suggest the role of PLA2 in MPTP and 6-OHDA induced neurotoxicity and oxidative stress. However, further studies are warranted to explore the therapeutic potential of PLA2 inhibitors for the treatment of Parkinson's disease.

Experimental study of the protection of ischemic preconditioning to spinal cord ischemia

BACKGROUND

Since the advent of ischemic preconditioning in myocardium, more and more attention has been paid to ischemic preconditioning in the central nervous system (CNS). This study was designed to evaluate the protective effect of ischemic preconditioning on spinal cord ischemia.

METHODS

Interventional neuroradiological techniques were used to induce spinal cord ischemia in a rabbit model. Hydrogen electrode technique was used to determine the regional blood flow of the spinal cord. Catecholamines and their metabolites were measured by high performance liquid chromatography (HPLA). Spinal cord evoked potentials were recorded to show spinal cord neurofunction.

RESULTS

After 5 minutes ischemic preconditioning with 20 minutes reperfusion, the regional spinal cord blood flow (rSCBF) was increased, as may be seen by the slight increase of catecholamine, especially NE. This is in positive proportion to the cAMP and indicates the enhancement of the metabolic activities of the spinal cord. After 30 minutes of irreversible ischemia, the great increase in catecholamine caused vascular spasm, endotheliocyte fissure, multiple hemorrhagic suffusion, and necrosis, which would injure the spinal cord as a result. The slight increase of the rSCBF and the maintenance of the rSCBF after irreversible ischemia may enhance the protection of ischemic preconditioning to the spinal cord neurofunction, which was proved by spinal cord evoked potentials (SCEPs).

CONCLUSIONS

Our study showed that 5 minutes of ischemic preconditioning can increase the rSCBF, enhance the tolerance of the spinal cord to irreversible ischemia, and protect the neurofunction of the spinal cord. The biological mechanism of the protective effect of ischemic preconditioning to spinal cord ischemia should be further studied.

Tolerance to beta,beta'-iminodipropionitrile (IDPN)-induced neurobehavioural and vestibular toxicity in diabetic rats

The present investigation was undertaken to study the neurotoxic effects of beta,beta'-iminodipropionitrile (IDPN) in normal, diabetic and insulin-treated diabetic rats. Sprague-Dawley male rats were divided into five groups: control, IDPN, diabetes, diabetes plus IDPN and diabetes plus insulin plus IDPN. The diabetes was induced with a single i.p. injection of streptozotocin (50 mg kg(-1)). One month after the induction of diabetes, the rats were treated with IDPN (100 mg kg(-1), i.p.) daily for 11 days. One of the diabetic groups treated with IDPN also received daily injection of insulin (25 U kg(-1), s.c.), 1 h before IDPN. The rats were observed daily for abnormal head movements and circling. The grip strength of the forelimbs was also measured. In the IDPN group the dyskinetic symptoms appeared on the 8th day, whereas the onset of dyskinesia was on the 12th day in IDPN-treated diabetic rats. The incidence and severity of dyskinesia were significantly higher in IDPN-treated normal (non-diabetic) rats as compared to IDPN-treated diabetic rats. The treatment of diabetic rats with insulin normalized striatal dopamine (DA) turnover but partially reversed diabetes-induced protection against IDPN dyskinesia. There was severe degeneration of sensory hair cells in crista ampullaris of IDPN-treated normal rats, whereas the diabetic rats showed significant protection against IDPN-induced vestibular hair cell degeneration. In conclusion, our study clearly demonstrates that diabetic rats are resistant to IDPN-induced neurobehavioural and vestibular toxicity. The results also show that diabetes-induced protection against IDPN-induced dyskinesia can be partially reversed by insulin. The mechanism behind the decreased vulnerability of diabetic animals to IDPN remains to be resolved. Further studies are warranted to investigate this paradoxical phenomenon.

Effect of chronic administration of magnesium sulfate on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced neurotoxicity in mice

This investigation was aimed to study the effect of magnesium on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity in mice. Four groups of mice were given magnesium sulfate (MgSO4.7H2O) in drinking water at four different concentrations of 0.0 g/l (control), 2.5 g/l (low), 5.0 g/l (medium) and 10.0 g/l (high) respectively for a period of 16 weeks; these animals also received MPTP (30 mg/kg, intraperitoneally daily) during the last five days of Mg treatment. Other four groups of mice were given similar dose regimen of MgSO4 but received injections of saline instead of MPTP. Seventy-two hr after the last dose of MPTP, neurobehavioural studies including locomotor activity, pole climbing test and heart nociception test were performed and striata were collected for the analysis of dopamine. The results of this study show that treatment of mice with MgSO4 or MPTP individually has no effect on their behaviour. Concomitant administration of low dose of MgSO4 (2.5 g/l) along with MPTP produced increase in motor activity and latency to heat stimuli; whereas medium and high doses of MgSO4 in combination with MPTP produced opposite (as compared to low dose) effects resulting in a decrease in motor activity and latency to heat stimuli and increase in pole climbing time. However, MgSO4 dose-dependently exacerbated MPTP-induced depletion of striatal dopamine. The mortality was drastically increased (30-55%) in the animals receiving combined treatments of MPTP and MgSO4 as compared to the mice treated with MPTP alone (12%). This study clearly points towards the ability of MgSO4 to modify MPTP-induced neurotoxicity.

Endogenous neuropeptides in patients with acute traumatic head injury. II: Changes in the levels of cerebrospinal fluid substance P, serotonin and lipid peroxidation products in patients with head trauma

The cerebrospinal fluid (CSF) levels of substance P (SP), serotonin (5-HT) and lipid peroxidation (LPx) products were measured in patients with traumatic head injury and then compared to the levels obtained from control subjects. CSF samples were collected from 45 patients (31 male, 14 female, aged 19.2 +/- 17.79) within 24 h of the head trauma and the control CSF samples were obtained from 25 healthy subjects (23 male, 2 female, aged 51.44 +/- 17.6 years) having minor surgical operations under spinal anaesthesia. CSF SP and 5-HT levels in patients with head trauma were significantly lower than the levels in controls (P < 0.005, P < 0.001, respectively). On the other hand, the CSF Lpx products were significantly increased in patients with head trauma (P < 0.001). No significant correlation was found between the CSF changes and the admission Glasgow Coma Scale scores of the patients. This study constitutes the second part of our work on endogenous neuropeptides in patients with traumatic head injury and it emphasizes the role of SP, 5-HT and lipid peroxidation as additional endogenous factors in traumatic head injuries.

Norepinephrine modulates excitability of neonatal rat optic nerves through calcium-mediated mechanisms

We report that norepinephrine markedly increases excitability of neonatal rat optic nerves. To investigate the mechanisms of the norepinephrine-induced excitability increase, we studied isolated optic nerves from 42 neonatal (< three days old) and five adult (> three months old) Long-Evan's hooded rats. Norepinephrine (10(-6), 10(-5) and 10(-4) M) rapidly and reversibly increased the amplitude (mean +/- S.D.: 3.5 +/- 1.7%, 12.1 +/- 2.8% and 35.6 +/- 8.4%) of compound action potentials elicited by submaximal stimulation of neonatal optic nerves. The beta-1 adrenoceptor antagonist atenolol (10(-5) M) blocked the norepinephrine-induced increase in excitability but the alpha antagonist phentolamine (10(-5) M) did not. The beta agonist isoproterenol (10(-5) and 10(-4) M) increased response amplitudes (8.7 +/- 4.1% and 25.8 +/- 4.6%) but the alpha-1 agonist methoxamine and alpha-2 agonist clonidine did not. The beta antagonist propranolol blocked the isoproterenol effect. Replacing Ca2+ with Mg2+ or adding 0.8 mM of Cd2+ reversibly blocked the norepinephrine effects. Extracellular K+ concentrations did not change in optic nerves during norepinephrine application. Blockade of K+ channels with apamin (10(-6) M) or tetraethylammonium (10(-3) M) did not prevent the excitatory effects of norepinephrine. Adult rat optic nerves were insensitive to both norepinephrine (10(-4) M) and isoproterenol (10(-4) M). Our results indicate that norepinephrine increases neonatal optic axonal excitability through Ca(2+)-dependent mechanisms. The data suggest that the adrenoceptors are situated on the axons, that the excitability changes are not due to changes in extracellular K+ concentration or K+ channels sensitive to apamin or tetraethylammonium. The sensitivity of rat optic nerves to norepinephrine declined with age. Axonal adrenoceptors may play a role in optic axonal development and injury.